column.dart

final column = OutVar<Column>();

init(
  Center(
    child: Column(
      outVar: column,
      space: 20,
      align: Align.start,
      children: [
        Box(
          width: 100,
          height: 100,
          color: 'LightSalmon',
          onClick: (self) {
            (self as Box);
            self.width += 40;
            if (self.width > 800) {
              self.width = 100;
            }
          },
        ),
        Box(
          width: 200,
          height: 100,
          color: 'LightSkyBlue',
          onClick: (_) {
            column.space += 5;
            if (column.space > 100) {
              column.space = 1;
            }
          },
        ),
        Box(
          width: 80,
          height: 100,
          color: 'SlateGrey',
          onClick: (_) {
            column.add(
              Box(
                width: 200,
                height: 10,
                color: 'SlateGrey'
              ),
            );
          },
        ),
        Box(
          width: 400,
          height: 50,
          color: 'MediumAquaMarine',
          onClick: (_) {
            if (column.align == Align.start) {
              column.align = Align.center;
            } else {
              column.align = Align.start;
            }
          }
        ),
      ],
    ),
  ),
);

demo.md

chrome_YQia1XWxml.mp4